How does one create a hypothesis while insisting upon a category of phenomena, namely "natural," that has no limits in either direction? Any observer at any time can ascribe the word "natural" to any phenomenon he observes, even if at bottom it is "supernatural." Furthermore, the capacity to hypothesize does not extend to the fundamental assumptions with which one undertakes science.
Hypotheses are but one tool of many in the arsenal of scientific inquiry. They neither define science, nor are they coterminous with science. By requiring the word "natural" as part of the definition of science, you yourself have introduced a concept that cannot be scientifically tested.
A supernatural ultimate creator of forces is not within the purview of science.
If by "purview" you mean such an entity cannot be physically grasped and made available for direct comment and direct observation, you may be right. But it is well within the purview of science to make inferences based upon organized matter that behaves according to predictable laws. It is not within the purview of science to declare from the outset than an intelligent designer will never be available in a more direct sense.
Inasmuch as theories are a general way of explaining a set of phenomenon, and inasmuch as science is speculative by nature, it is certainly well within reason and established scientific pursuit to approach the presence of organized matter that behaves under predictable laws as if it were intelligently designed by God.
There is no small hypocrisy in saying "the universe only gives the appearance of design yet it must have evolved by natural causes" when the simpler explanation is that it is designed in the first place. How is it that "appearances" are somehow lathered up and called "science" when the nature of the universe is constrained to particle matter that does not change on a whim, and therefore better understood as intelligently designed? One could just as easily say, "the universe only gives the appearance of evolving." Is such a statement less scientific than saying "the universe only gives the appearance of design?"
Come on Fester, you know exactly what's meant by the word.